1. Field of the Invention
This invention relates to a guidance assembly for attachment to a shaping tool or an assembly which may be integral with a shaping tool used for cutting, deburring, trimming, and removing edges or fins and the like of workpieces, more particularly, to a jeweler's cutting or grinding assembly for use in setting gemstones.
2. Description of the Prior Art
Jewelers' flexible shaft handpieces which can be used for gem setting, undercutting, and texturing are commonly provided without a guiding assembly necessitating that the operator exercise manual control of the guidance of the driven drill or bur which performs the cutting of the workpiece. Tools for deburring, chamfering, trimming, and removing edges of workpieces are disclosed in U.S. Pat. No. 4,279,554. A tool for trimming of edges is disclosed in U.S. Pat. No. 4,504,178. Neither of these tools are used in association with an attachment which guides the cutting, deburring, or chamfering action of the drill or bur. A grinding guide assembly for a hand-held grinding machine for buttons used with a button drill bit is disclosed in U.S. Pat. No. 5,138,797. The hand-held grinding machine disclosed in this patent can be driven pneumatically, hydraulically or electrically depending upon the power source available at the site where the machine is used. The proper grinding of buttons requires that the operator be able to rotate the drilling machine around the button at the grinding point while the grinding machine is operated. Accordingly, it is necessary to hold the grinding disc centered on one single point in relation to the button. This cannot be achieved with a conventional hand-held grinding machine, therefore, necessitating the use of a grinding guide assembly.
A drill stop for determining the depth of holes drilled by an electric hand drill is disclosed in U.S. Pat. No. 2,978,931. A cutting tool adapted to be manually guided over the surface of a work piece is disclosed in U.S. Pat. No. 2,238,304 and a guide for a precision shaping tool is disclosed in U.S. Pat. No. 5,152,644.
Similarly, the highly accurate setting of precious stones, whether channel, bead, or prong setting.; which may involve the undercutting of a channel in the workpiece has been difficult to achieve simply by using conventional hand-held drills and burs mounted upon flexible shaft handpieces.